Bummer guys.
I've noticed the first time I charge my ZZ SE it runs way longer than it ever does after that. The first time I charged my Mach 1, it ran for over 15 min with out the lights. (i hardly ever plug the lights in.) Now it will go for 5-10 min.
Have you guys tried double charging them? You can safely charge them twice. (Thanks gtr2112)
If this doesn't give you a longer run time, then just return them to RS. Because you should get more than 2 minutes, with or with out the lights.